A team of oil spill experts from the United Nations Environment Program is in Ogoni, southern Nigeria, to assess the impact of oil pollution on the region. The visit comes at a time of new revelations on the level of pollution in the oil-rich Niger Delta.

The U.N. team's primary task is to examine reports of massive oil pollution in Ogoni, a relatively small community in southeastern Nigeria.

Shell Oil company was compelled to shut down its operations in Ogoni ten years ago as a result of a high-profile protest campaign against the company.

The Nigerian government recently ordered Shell to resume oil production in Ogoni within one year or lose its concession.

A government-sponsored campaign to reconcile Ogoni communities with Shell has been bogged down by deep-seated animosity and suspicion.

Some indigenous groups believe the current attempt to clean up oil pollution in the area is a surreptitious attempt to facilitate the return of Shell to Ogoni.

The Movement for the Survival of the Ogoni People, known as MOSOP, says it is wrong for the authorities to present the clean up as the only issue that matters to the Ogoni people.

"If they are looking at the issue of remediation, what happens to the social impact of pollution?" asked Bari-Ara Kpala, a spokesman for the group. "What happens to the economic impact of pollution on the people, particularly as it relates to livelihood? You know the pollution in Ogoni has completely destroyed the people's livelihood and if you must deal with it, you don't need to pick out only one narrow bit out of the lot. You need to look at what needs to be done to address the whole issue of environmental destruction."

A recent report by a panel of independent international experts say about 1.5 million tons of oil has been spilt in the Niger Delta over the past 50 years.

The report says oil spills have done colossal damage to the fragile mangrove forests and wiped out rare species, including primates, fish, turtles and birds.

The study, compiled by World Wildlife Fund-UK (WWF UK), the World Conservation Union and the Nigeria Conservation Foundation, concluded that pollution is destroying the livelihood of 20 million people in the region.

The delta is now considered one of the five most polluted spots in the world.

Oronto Douglas, an environmentalist in the Niger Delta, says the study of the environmental crisis in Ogoni should be extended to the entire Delta region.

"An assessment of spill by an independent body should be welcomed throughout the Delta, because one of the key things people are demanding is a clean, healthy and sustainable environment and access like this can be a prelude to a full-blown clean-up campaign," he explained. "And it will be necessary to extend such a mission throughout the Delta, especially if the ultimate goal is to ensure environmental justice and sustainable development."

The report concluded that the damage done by oil and gas production was one of the factors responsible for the instability and violence in the region, including the sabotage of oil facilities.